Bulb socket

Abstract: A bulb socket (A) for holding a wedge base bulb (B) which has a bulb portion (2), a base portion (3) and power terminals (5), the bulb socket (A) comprising a socket body (10), supplying terminals (13) and holder members (14). The socket body (10) is provided for receiving the base portion (3) of the wedge base bulb (B). The supplying terminals (13) are electrically connecting with the respective power terminals (5) of the wedge base bulb (B) under a predetermined pressure, and are held by the socket body (10). The holder members (14) are holding the base portion (3) of the wedge base bulb (B) therebetween under a predetermined pressure. And the holder members (14) are separate from the supplying terminals (13), and are attached to the socket body (10).

Description: This invention relates to a bulb socket for holding a wedge base bulb to supply electric power thereto. One conventional socket for holding a wedge base bulb to supply electric power thereto is disclosed in Japanese Utility Model Unexamined Publication No. 2-47787. In this construction, a pair of metal members is attached to a socket body, and a supplying terminal resiliently-engageable portion, which is formed on each of these metal members, is exposed in a bulb insertion hole. When a base portion of the wedge base bulb is fitted in the bulb insertion hole, two power terminals mounted on the base portion are contacted respectively with the supplying terminals of the two metal members, so that electric power can be supplied to the wedge base bulb. At the same time, rugged portions formed on the base portion engage the resiliently-engageable portions of the two metal members, respectively, so that the base portion is held between the two resiliently-engageable portions to thereby prevent the wedge base bulb from withdrawal. When attaching the wedge base bulb to the socket, it is desirable that a contact resistance at the contact location between each supplying terminal and the associated power terminal be low, and it is also desirable that a resilient force at that contact location between each resiliently-engageable portion and the associated rugged portion be large. However, in the conventional construction, the supplying terminal portion, for supplying electric power to the wedge base bulb, and the resiliently-engageable portion, for holding the wedge base bulb, are formed as an integral metal member made of a single material. Therefore, the material of the metal member is required to perform both the function to reduce the contact resistance and the function to increase the resilient force of the resiliently-engageable portion; however, there exists no material which can achieve both functions at a high level and at low costs, and as a result both functions have not been entirely satisfactory. In the meantime, a requirement for such a bulb socket, when used on a vehicle body, is that the amount of rearward projection of a light device should be reduced. Therefore, there is known a construction in which the other end of each metal member exposed in a bulb insertion hole is extended perpendicularly to the bulb insertion hole, so that the whole of the bulb socket assumes an L-shape. In this case, the metal member is also of an L-shape, and hence can not be inserted into a casing through the bulb insertion hole after the casing is molded, and therefore there has been used a method (hereinafter referred to as "insert molding" in which a resin is molded on the periphery of the metal members while holding the metal members. However, setting apart from the case where the metal member has a simple configuration, when the configuration is complicated as shown in the above-mentioned publication, such an insert molding is difficult because a gap may be formed between the metal member and a mold during the insert molding as a result of lowered dimensional accuracies, so that a resin flows into such a gap, and also the metal member may interfere with the mold, and the metal members can not be sufficiently held by the mold. As a result, by an injection pressure, the metal members are deformed, and the resin is caused to flow. Furthermore, if the mold is complicated, it is difficult to feed the parts by a part feeder in an automated production. DE-A-20 62 650 discloses a bulb socket for holding a wedge base bulb, from said bulb socket the present invention starts from. In case of this known bulb socket the holding means for the bulb or its socket, respectively, is constituted by plate members lying in a juxtaposed relationship to the supplying terminals and accordingly the base portion of the bulb is only held between the supplying terminals and the holding means being in engagement with the front and rear longsides of the the base portion. Thus, this known bulb socket does not hold the bulb's socket firmly and due to shocks or vibrations, which unavoidibly occur in case of e.g. automobiles the socket might become loose and the bulb fails to emit light. It is thus an object of this invention to provide a construction in which the function to reduce a contact resistance at power supply portions for a wedge base bulb and the function to secure a high holding force at those portions of engagement with the wedge base bulb are both achieved at a high level, and the manufacture can be carried out easily even if the configuration of metal members is complicated. A solution of this object is achieved by what is claimed in claim 1, whereas the subclaims contain advantageous modifications. Accordingly, there is provided a bulb socket for holding a wedge base bulb which has a bulb portion, a base portion and power terminals, said bulb socket comprising: a socket body made of resin for receiving the base portion of the wedge base bulb within a bulb insertion hole; supplying terminals for electrically connecting with the respective power terminals of the wedge base bulb under a predetermined pressure, said terminals being held by said socket body; and holding means made of metal for holding the base portion of the wedge base bulb under a predetermined pressure, said holding means being separate from said supplying terminals and being attached to said socket body, wherein said holding means comprises: a first engagement portion for engaging said holding means with said socket body; a second engagement portion for engaging said holding means with the base portion of the wedge base bulb; and a play restraining portion for restraining a play between said holding means and the base portion of the wedge base bulb. The bulb socket according to the present invention is furthermore characterized in that said holding means comprises two perpendicularly-disposed plate portions being disposed in said bulb insertion hole to be in intimate contact with two perpendicularly-disposed inner surfaces of said bulb insertion hole, wherein said second engagement portion being provided in one of said plate portions and said play restraining portion being provided in the other one of said plate portions. Thus, the holding means has two perpendiculary-disposed plate portions, wherein one engagement portion is disposed in one of the plate portions and the play restraining portion being provided in the other one of the plate portions. By means of this it is possible to hold the base portion of the bulb not only from one side, as this is the case in e.g. DE-A-20 62 650, but at least from two perpendiculary-oriented sides and thus to increase holding strength, so that the bulb is more securely held against withdrawal and against shaking. In other words, in case of the present invention the base portion of the bulb is held at least at one long and one short side by means of the perpendiculary disposed second engagement portion and play restraining portion and is thus firmly held to withstand shocks or vibrations without getting loose. Furthermore, each of the supplying terminals for supplying electric power to the wedge base bulb is separate from the holder member for holding the wedge base bulb. Therefore, a material of the supplying terminal is selected to have such a nature as to achieve only the function to reduce a contact resistance at that portion of contact between the supplying terminal and the power terminal of the wedge base bulb. Also, a material of the holder member is selected to have such a nature as to achieve only the function to increase a resilient holding pressure at those portions of the holder member which hold the wedge base bulb. The holding force by the holder member can be increased, for example, merely by increasing the sheet thickness thereof. Particularly, even if the same material is used, the bulb holding force can be increased merely by increasing the sheet thickness of the holder metal member. Of course, electrical connection is not needed for the holder member, and therefore in view of mechanical strength and the cost, stainless steel or the like can be selected as the material of the holder member. Furthermore, the supplying terminals integrally molded in the resin are separate from the holder member and are simple in shape. Therefore, the operation for forming such an integral construction can be carried out easily. As described above, in the present invention, the material nature of the supplying terminals for supplying electric power to the wedge base bulb is different from the material nature of the holder members for holding the wedge base bulb. Therefore, there is achieved an excellent advantage that the function to reduce the resistance of contact between the supplying terminal and the power terminal of the wedge base bulb, as well as the force of holding of the wedge base bulb by the holder members, can be both achieved at a high level. Said force of holding of the wedge base bulb by the holder members is even increased, if - according to the present invention - the holding means has two perpendiculary-disposed plate portions, wherein one engagement portion is disposed in one of the plate portions and the play restraining portion being provided in the other one of the plate portions, so that it is possible to hold the base portion of the bulb not only from one side, but at least from two perpendiculary-oriented sides. The supplying terminal is separate from the holder member, and with this arrangement each of them is more simplified in shape as compared with the case where the two are formed integrally with each other. This enables insert molding, and an efficiency of the operation, as well as reduction of the manufacturing cost can be achieved by carrying out such insert molding in an automated manner. This invention can be more readily understood from the following detailed description, which is to be taken in conjunction with the accompanying drawings, in which: Fig. 1 is a partly-broken, perspective view of a socket body; Fig. 2 is a cross-sectional view of the socket body as viewed in a direction perpendicular to a connector insertion hole in the socket body; Fig. 3 is a partly cross-sectional, side-elevational view of the socket body as viewed from the connector insertion hole side; Fig. 4 is a right side-elevational view of a supplying terminal; Fig. 5 is a front-elevational view of the supplying terminal; Fig. 6 is a plan view of the supplying terminal; Fig. 7 is a right side-elevational view of a holder metal member; Fig. 8 is a cross-sectional view of the holder metal member; Fig. 9 is a plan view of the holder metal member; and Fig. 10 is a perspective view of a wedge base bulb. A bulb socket A shown in Fig. 1 is adapted to hold a wedge base bulb B of the single filament type shown in Fig. 10. In the wedge base bulb B, a flattened base portion 3 is integrally molded on a lower portion of a bulb portion 2 which contains a filament 1 therein. Two lead wires 4 extended from a lower surface of the base portion 3 are folded respectively on opposite (right and left) sides of the base portion 3 to form power terminals 5. An upwardly-slanting projection 6 and an abutment projection 7 are formed on each of the opposite right and left sides of the base portion 3. A socket body 10 of the bulb socket A is made of a synthetic resin material. The socket body 10 has a bulb insertion hole 11 for receiving the base portion 3 of the wedge base bulb B, and a connector insertion hole 12 for connecting a power supply connector (not shown) thereto. The bulb insertion hole 11 and the connector insertion hole 12 are open perpendicularly to each other, and the socket body 10 thus assumes an L-shape as a whole, as shown in Fig. 2. Two supplying terminals 13 (shown in Figs. 4 to 6) for supplying electric power to the wedge base bulb B, as well as two holder metal members 14 (shown in Figs. 7 to 9) for holding the wedge base bulb B against withdrawal, are mounted on the socket body 10. The supplying terminal 13 is formed by bending an elongate strip of an electrically-conductive metal material which can keep a resistance of contact with the power terminal 5 of the wedge base bulb 5 to a low level. The supplying terminal 13 has one end portion defining a connector connecting portion 15 in the form of a flat strip, and a bulb connecting portion 16 formed by folding a tip portion of the other end portion extending in a direction perpendicular to the connector connecting portion 15. The two supplying terminals 13 are connected integrally with the socket body 10 by insert molding during the molding of the socket body 10 in such a manner that these supplying terminals are held against withdrawal and movement. In this connected condition of these supplying terminals 13, the connector connecting portions 15 of the two supplying terminals 13 are projected into the connector insertion hole 12 in juxtaposed relation to each other. The two bulb connecting portions 16 are disposed respectively on opposed right and left sides of the inner surface of the bulb insertion hole 11. The holder metal member 14 is formed by bending a sheet of metal having a high elastic coefficient into an L-shape which metal sheet is larger in thickness than the supplying terminal 13. A curved resilient engagement portion 17 is formed on and projected inwardly from one of two perpendicularly-disposed plate portions of the holder member 14 while a part of the other plate portion is stamped and slightly bulged inwardly to form a play restraining portion 18. Also, a part of each of the two plate portions is stamped and raised obliquely upwardly to form a withdrawal prevention portion 19. The two holder metal members 14 are forced into the bulb insertion hole 11 to be attached thereto in such a manner that the outer surfaces of their plate portions are held in intimate contact with the inner surface of the bulb insertion hole. In this attached condition, the resilient engagement portions 17 are disposed respectively on the right and left sides of the inner surface of the bulb insertion hole 11, and the play restraining portions 18 for the bulb are disposed respectively on the front and rear sides of the inner surface of the bulb insertion hole. Also, in the attached condition, the opposite side edges of the holder metal member 14 are fitted respectively in positioning grooves 20 in the bulb insertion hole 11, and the withdrawal prevention portions 19 are engaged respectively with notches 21 in the bulb insertion hole 11, thereby preventing the holder metal member 14 from shaking and moving in a withdrawing direction. For attaching the wedge base bulb B to the bulb socket A provided with the supplying terminals 13 and the holder metal terminals 14, the base portion 3 of the wedge base bulb B needs only to be pushed into the bulb insertion hole 11 of the bulb socket A. At this time, a slanting surface 6a of each of the upwardly slanting projections 6 of the base portion 3 abuts against the resilient engagement portion 17 of the corresponding holder metal member 14, and resiliently deforms the same gradually, and simultaneously when the abutment projection 7 abuts against an abutment portion 22 formed on the inner surface of the bulb insertion hole 11, the resilient engagement portion 17 is disengaged from the slanting surface 6a of the upwardly slanting projection 6 to be resiliently restored. As a result, the two resilient engagement portions resiliently hold the base portion 3 from the opposite sides thereof, and also are engaged respectively with upwardly-directed engagement surfaces 6b of the upwardly slanting projections 6. Also, the base portion 3 is resiliently held between the play restraining portions 18 of the holder metal members 14 in such a manner that the play restraining portions 18 are strongly pressed respectively against the front and rear sides of the base portion 3. As a result, the base portion 3 of the wedge base bulb B is held against withdrawal from the bulb insertion hole 11 and also against shaking. During the insertion of the base portion 3 into the bulb insertion hole 11, the bulb connecting portions 16 of the supplying terminals 13 are pressed to be slightly resiliently deformed, so that these portions 16 are contacted respectively with the power terminals 5 on the base portion 3 under a predetermined pressure, thus enabling the supply of electric power. The connector (not shown) is inserted in the connector insertion hole 12, and the connector connecting portions 15 of the supplying terminals 13 are fitted in and contacted with terminals of this connector, respectively, thus enabling the supply of electric power. On the other hand, the holder metal member 14 has a high elastic coefficient, and therefore a high holding force is provided at those portions of contact between the holder metal member 14 and the wedge base bulb B. Only the supplying terminals 13 are insert molded in the socket body 10, and the holder metal members 14 are not insert molded. Therefore, as compared with the case where the supplying terminals 13 and the holder metal members 14 are both inserted molded, the insert operation can be carried out more easily because of a simple shape of the insert members and also of the ease of holding the insert members in a mold. Since the supplying terminal 13 is separate from the holder metal member 14, each of them is simpler in shape as compared with the case where the two are formed into an integral construction, and therefore an improved efficiency of the operation, as well as the reduction of the manufacturing cost, can be achieved by carrying out the insert molding in an automated manner. The present invention is not limited to the above embodiment, and for example, the following modifications can be made: (a) Although the above embodiment has been described with respect to the bulb socket for holding the wedge base bulb of the single filament type, the present invention can also be applied to a bulb socket for holding a wedge base bulb of the double filament type. (b) Although the above embodiment has been described with respect to the bulb socket of a generally L-shape in which the bulb insertion hole 11 and the connector insertion hole 12 are open perpendicularly to each other, the present invention can be applied to a bulb socket of such a configuration that a bulb insertion hole and a connector insertion hole are open in opposite directions, respectively. In this case, supplying terminals may be attached by inserting these supplying terminals into one of the two insertion holes in a molded socket body, or the supplying terminals may be made integral with the socket body by insertion molding as in the above embodiment. The present invention is not limited by the embodiment described above and illustrated in the drawings, and various modifications can be made without departing from the subject-matter of the invention as defined by the appended claims.

Claims: A bulb socket for holding a wedge base bulb (B) which has a bulb portion (2), a base portion (3) and power terminals (5), said bulb socket comprising: a socket body (10) made of resin for receiving the base portion (3) of the wedge base bulb (B) within a bulb insertion hole (11); supplying terminals (13) for electrically connecting with the respective power terminals (5) of the wedge base bulb (B) under a predetermined pressure, said terminals (13) being held by said socket body (10); and holding means (14) made of metal for holding the base portion (3) of the wedge base bulb (B) under a predetermined pressure, said holding means (14) being separate from said supplying terminals (13) and being attached to said socket body (10), wherein said holding means (14) comprises: a first engagement portion (19) for engaging said holding means (14) with said socket body (10); a second engagement portion (17) for engaging said holding means (14) with the base portion (3) of the wedge base bulb (B); and a play restraining portion (18) for restraining a play between said holding means (14) and the base portion (3) of the wedge base bulb (B), characterized in that said holding means (14) comprises two perpendicularly-disposed plate portions being disposed in said bulb insertion hole (11) to be in intimate contact with two perpendicularly-disposed inner surfaces of said bulb insertion hole (11), wherein said second engagement portion (17) being provided in one of said plate portions and said play restraining portion (18) being provided in the other one of said plate portions. The bulb socket according to claim 1, wherein two of said holding means (14) are arranged inside said bulb insertion hole (11). The bulb socket according to claim 1 or 2, wherein said supplying terminals (13) are integrally molded into the resin of said socket body (10).

Inventors: OGAWA SHINJI, OGAWA, SHINJI, OGAWA, SHINJI, C/O SUMITOMO WIRING SYSTEMS, LTD.
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1994
Main classification: H01R33
IPC codes: H01R33